From 6e5aa7efb27aec7e55b6463fa2c8db594c4226fa Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 4 Feb 2008 23:50:03 -0500 Subject: virtio: reset function A reset function solves three problems: 1) It allows us to renegotiate features, eg. if we want to upgrade a guest driver without rebooting the guest. 2) It gives us a clean way of shutting down virtqueues: after a reset, we know that the buffers won't be used by the host, and 3) It helps the guest recover from messed-up drivers. So we remove the ->shutdown hook, and the only way we now remove feature bits is via reset. We leave it to the driver to do the reset before it deletes queues: the balloon driver, for example, needs to chat to the host in its remove function. Signed-off-by: Rusty Russell --- drivers/virtio/virtio.c | 12 ++++++++++-- drivers/virtio/virtio_ring.c | 11 ----------- 2 files changed, 10 insertions(+), 13 deletions(-) (limited to 'drivers/virtio') diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index 303cb6f9010..7dddb186093 100644 --- a/drivers/virtio/virtio.c +++ b/drivers/virtio/virtio.c @@ -102,9 +102,13 @@ static int virtio_dev_remove(struct device *_d) struct virtio_driver *drv = container_of(dev->dev.driver, struct virtio_driver, driver); - dev->config->set_status(dev, dev->config->get_status(dev) - & ~VIRTIO_CONFIG_S_DRIVER); drv->remove(dev); + + /* Driver should have reset device. */ + BUG_ON(dev->config->get_status(dev)); + + /* Acknowledge the device's existence again. */ + add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); return 0; } @@ -130,6 +134,10 @@ int register_virtio_device(struct virtio_device *dev) dev->dev.bus = &virtio_bus; sprintf(dev->dev.bus_id, "%u", dev->index); + /* We always start by resetting the device, in case a previous + * driver messed it up. This also tests that code path a little. */ + dev->config->reset(dev); + /* Acknowledge that we've seen the device. */ add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE); diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index dbe1d35db32..9849babd6b3 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -173,16 +173,6 @@ static void detach_buf(struct vring_virtqueue *vq, unsigned int head) vq->num_free++; } -/* FIXME: We need to tell other side about removal, to synchronize. */ -static void vring_shutdown(struct virtqueue *_vq) -{ - struct vring_virtqueue *vq = to_vvq(_vq); - unsigned int i; - - for (i = 0; i < vq->vring.num; i++) - detach_buf(vq, i); -} - static inline bool more_used(const struct vring_virtqueue *vq) { return vq->last_used_idx != vq->vring.used->idx; @@ -278,7 +268,6 @@ static struct virtqueue_ops vring_vq_ops = { .kick = vring_kick, .disable_cb = vring_disable_cb, .enable_cb = vring_enable_cb, - .shutdown = vring_shutdown, }; struct virtqueue *vring_new_virtqueue(unsigned int num, -- cgit v1.2.3